|Heterozygotes have curly whiskers and progressive hair loss commencing 8-12 days after birth by which time the skin is loose and wrinkled. By weaning most of the fur has gone from heterozygotes, by adulthood they are bald. Opening data are inconsistent, but suggest that some, if not all, homozygotes are lost pre-implantation. Openings from 3H1 females crossed to heterozygous males indicate little or no loss of Mut1231/+ prior to birth. Reciprocal openings suggest that heterozygous females have impaired ability to carry large litters to term. Viability of heterozygotes to weaning is good. Penetrance of the mutation on a 3H1 background and on outcrossing to Mus castaneus is also good.
Mapping data (which position Mut1231 on Chr11) gave the following linkage:
Cross 1: Mut1231 - 14.55 cM +/- 3.36 cM - Re.
Cross 2: D11Mit1 - 30 cM +/- 6.48 cM - Mut1231 - 22 cM +/- 5.86 cM - D11Mit329.
Intercrosses of mice heterozygous for both Mut1231 and Foxn1<nu> failed to produce any phenotypically wild-type pups out of 213 offspring scored indicating that Mut1231 and Foxn1<nu> are either allelic, or closely linked. Unlike Foxn1<nu>/Foxn1<nu>, Mut1231/+ mice are not athymic at weaning. Spontaneous, dominant mutation found in 3H1 stock.|